The present invention relates to a cooling apparatus for machinery and more particularly to a cooling apparatus for machinery utilizing a vaporizable liquid refrigerant.
In this kind of a cooling apparatus, since a heat generating body such as the core or windings of a transformer is immersed in a vaporizable liquid refrigerant and is cooled by the latent heat of vaporization of the liquid, the cooling efficiency is high. In addition, since no mineral oil is used, advantages such as nonflammability, compactness, lightness, etc. can be obtained. Therefore, this kind of cooling apparatus has recently drawn much attention.
An example of this kind of the cooling apparatus is shown in FIG. 1 of the attached drawings.
In FIG. 1, there is shown a tank 1 having its upper end sealed by a cover 101. The machinery body 2 of the machinery to be cooled, e.g. a transformer is contained within the tank 1, the transformer comprising a core 201, a low voltage winding 202, and a high voltage winding 203, both windings 202 and 203 being wound around the core 201. The body 2 is provided with a first duct 204 between core 201 and low voltage winding 202 and a second duct 205 between low and high voltage windings 202 and 203, respectively. A liquid refrigerant 3 such as fleon 11 or the like, i.e. a vaporizable liquid refrigerant, is sealed within the tank 1 so that the machinery body 2 is entirely submerged therein. A condenser 4 is provided to condense the refrigerant vapor which is generated from the liquid refrigerant 3 when it cools the machinery body 2 by its latent heat of vaporization, this condensation generating condensed refrigerant 401. The condenser 4 is provided with a number of cooling tubes 402 through which passes the refrigerant vapor. One end portion of the condenser 4 and the tank 1 are connected together by a vapor pipe 5 which leads the refrigerant vapor generated from the liquid refrigerant 3 within tank 1 to the condenser 4. The other end portion of the condenser 4 and the tank 1 are connected by a return pipe 6 which returns the condensed refrigerant 401 which has condensed from the vaporized refrigerant in the condenser 4 to the tank 1, the lower end of the return pipe 6 extending to a point below the level of the liquid refrigerant 3 within the tank 1. As can be seen, the cooling tubes 402 of the condenser 4 are inclined so that the end near the return pipe 6 is lower than the opposite end.
The operation of the cooling apparatus described so far is as follows.
The heat generated by the core 201, and the low and high voltage windings 202 and 203, respectively, is transferred from their surfaces to the surrounding liquid refrigerant 3 within the tank 1 as well as to the liquid refrigerant 3 contained within the first and second ducts 204 and 205, respectively, the refrigerant liquids 3 being in contact with the peripheral surfaces of the ducts. Thus, the liquid refrigerant 3 absorbs the heat from the core 201 as well as from the low and high voltage windings 202 and 203, respectively. As a result, it transforms from the liquid to the vapor phase, and cools the core 201 as well as the low and high voltage windings 202 and 203, respectively, by this vaporization. The refrigerant vapor produced from the liquid refrigerant 3 is led to the cooling tubes 402 of the condenser 4 through the vapor pipe 5, the refrigerant vapor having its heat dissipated to the surrounding atmosphere to be condensed and thus transformed into the condensed refrigerant 401. The condensed refrigerant 401 flows through the inclined cooling tubes 402 towards the return pipe 6 to be returned again to the tank 1 through the return pipe 6. As the refrigerant vapor within the cooling tubes 402 condenses, the vapor pressure within the cooling tubes 402 decreases.
As a result, the refrigerant vapor produced from the liquid refrigerant 3 by the heat generated from the core 201 as well as the low and high voltage windings 202 and 203, respectively, flows into the cooling tubes 402 of the condenser 4. Thus, the cooling cycle is continuously repeated to continuously cool the core 201 as well as the low and high voltage windings 202 and 203, respectively.
Since the conventional cooling apparatus has a construction and operation such as that described above, the cooling tubes 402 of the condenser 4 have to be inclined, and the structure of the condenser 4 and the tank 1 is made complicated, increasing manufacturing costs.
U.S. Pat. No. 4,173,996 to Linden W. Pierce discloses an invention entitled "Heat Exchange Arrangement for Vaporization Cooled Transformers", wherein a condenser or a heat exchanger is provided with a plurality of inclined cooling tubes, and the condenser and the tank are connected together by a vapor intake pipe and a condensed coolant return pipe arranged at opposite ends of the heat exchanger. Thus, this patent differs from the present invention in that in the latter the cooling tubes are arranged horizontally, and the condenser and the tank are connected together by pipes at both ends of the condenser, each pipe acting simultaneously as a vapor intake pipe and a condensed coolant return pipe.